Degradable Porous Carboxymethyl Chitin Hemostatic Microspheres

War,traffic accidents and surgical operations may lead to severe bleeding,but traditional hemostasis methods such as pressure and suture are difficult to achieve the requirements of rapid hemostasis.Therefore,the development of hemostatic materials which can stop bleeding fast without any side effects are of great significance in daily life.Carboxymethyl chitin(CMCH)has good hydrophilicity and biocompatibility as a derivative of chitin,,is potential to be used in rapid hemostasis and wound healing.In this thesis,thermosensitive CMCH was synthesized under homogeneous and mild conditions.On the premise of retaining most of acetyl groups,the CMCH obtained good hydrophilia and biodegradability.At the same time,CMCH microspheres with porous structure were prepared to further improve the hemostatic capacity of the raw CMCH.Its biological safety and hemostatic effect in vivo and in vitro were investigated.The main research contents of this thesis are listed as follows:(1)A series of CMCHs with different degrees of substitution(DS)were synthesized under homogeneous Na OH/urea and mild conditions,and CMCH microspheres(CMCH-MS)were prepared through heating by physical crosslinking without use of any crosslink agent.Different DS of CMCH and various preparation conditions were investigated,and the experimental results such as water-swelling performance,in vitro enzymatic degradation rate,showed that the CMCH-MS with the DS of 0.13 had a good porous spherical structure,rapid water absorption rate and good biodegradability.(2)CMCH-0.13-MS was selected as the representative research object.We tested its cytotoxicity,hemolytic ratio,and in vitro coagulation effect.The cytotoxicity and hemolysis evaluation showed that the CMCH-0.13-MS were non-cytotoxic,and had low hemolytic potential.The results of activated partial thromboplastin time(APTT),prothrombin time(PT)and clotting time(CT)experiments indicated that the hemostatic performance of CMCH-0.13-MS was mainly due to the absorption of water and the concentration of coagulation factors in the blood,which was benefited from the porous structure of microspheres.In the rat femoral artery,rat tail and rat liver models,CMCH-0.13-MS showed a good hemostatic effect compared to the positive groups.The CMCH-MS is expected to be a new hemostatic material with high efficiency,biological safety,low cost,convenient preparation method,good biodegradability and biocompatibility in clinic for controlling hemorrhaging.